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This appears to be amateur/hobby/pleasure (no income) for which only a B2 visa would be needed. B2 is one of the categories covered under the VWP.
The more important question will be how to convince immigration that you are not intending to sell those photo's afterwards. Immigration does not work on a presumption of innocence. Signing up for a photography course (not as part of a format study program) might help show your amateur status, yet is compatible with B2/VWP.